A multiple-oscillator mechanism underlies antigen-induced Ca2+ oscillations in Jurkat T-cells

T-cell receptor stimulation triggers cytosolic Ca2+ signaling by inositol-1,4,5-trisphosphate (IP3)-mediated Ca2+ release from the endoplasmic reticulum (ER) and Ca2+ entry through Ca2+ release-activated Ca2+ (CRAC) channels gated by ER-located stromal-interacting molecules (STIM1/2). Physiologically, cytosolic Ca2+ signaling manifests as regenerative Ca2+ oscillations, which are critical for nuclear factor of activated T-cells-mediated transcription. In most cells, Ca2+ oscillations are thought to originate from IP3 receptor-mediated Ca2+ release, with CRAC channels indirectly sustaining them through ER refilling. Here, experimental and computational evidence support a multiple-oscillator mechanism in Jurkat T-cells whereby both IP3 receptor and CRAC channel activities oscillate and directly fuel antigen-evoked Ca2+ oscillations, with the CRAC channel being the major contributor. KO of either STIM1 or STIM2 significantly reduces CRAC channel activity. As such, STIM1 and STIM2 synergize for optimal Ca2+ oscillations and activation of nuclear factor of activated T-cells 1 and are essential for ER refilling. The loss of both STIM proteins abrogates CRAC channel activity, drastically reduces ER Ca2+ content, severely hampers cell proliferation and enhances cell death. These results clarify the mechanism and the contribution of STIM proteins to Ca2+ oscillations in T-cells.

SGLT inhibitors as new therapeutic tools in the treatment of diabetes

Recently, the idea has been developed to lower blood glucose blood glucose levels in diabetes by inhibiting sugar reabsorption sugar reabsorption in the kidney kidney . The main target is thereby the early proximal tubule proximal tubule where secondary active transport secondary active transport of the sugar is mediated by the sodium-D: -glucose D-glucose cotransporter SGLT2 SGLT2 . A model substance for the inhibitors inhibitors is the O-glucoside O-glucoside phlorizin phlorizin which inhibits transport transport competitively. Its binding to the transporter involves at least two different domains: an aglucone binding aglucone binding site at the transporter surface, involving extramembranous loops extramembraneous loops , and the sugar binding sugar binding /translocation site buried in a hydrophilic pocket of the transporter. The properties of these binding sites differ between SGLT2 and SGLT1 SGLT1 , which mediates sugar absorption sugar absorption in the intestine intestine . Various O-, C-, N- and S-glucosides have been synthesized with high affinity affinity and high specificity specificity for SGLT2 SGLT2 . Some of these glucosides are in clinical trials clinical trials and have been proven to successfully increase urinary glucose excretion urinary glucose excretion and to decrease blood sugar blood sugar levels without the danger of hypoglycaemia hypoglycaemia during fasting fasting in type 2 diabetes type 2 diabetes .

Protein kinase C mediated intracellular signaling pathways are involved in the regulation of sodium-dependent glucose co-transporter SGLT1 activity

The sodium-dependent glucose co-transporter (SGLT1) is regulated by protein kinases. The aim of the present study was to examine the role of protein kinase C (PKC) in the regulation of rabbit (rb) SGLT1 activity as determined by alpha-methyl-D-glucopyranoside (AMG) uptake and to identify the cellular mechanisms involved in this process. For this purpose Chinese hamster ovary cells expressing rbSGLT1 (CHO-G6D3) were treated with PKC activators and inhibitors. PKC activators did not exert any effect on AMG uptake, as corroborated by mutation of the putative phosphorylation sites of PKC. In contrast, the PKC inhibitor bisindolylmaleimide I (BIM) increased AMG uptake. This effect was associated with translocation of rbSGLT1 from the intracellular pool to the plasma membrane demonstrated by pre-treatment of G6D3 cells with cytochalasin D that abolished the effect of BIM. In addition, intracellular signaling pathways (p38/MAPK, ERK/MAPK, JNK/MAPK, and PI3K/Akt/mTOR) were associated with PKC-regulated AMG uptake. Moreover, rbSGLT1 mRNA level was higher in BIM-treated cells than in untreated, control cells. This effect was completely abolished by actinomycin D treatment. The present study demonstrates that PKC regulates rbSGLT1 activity via a complex intracellular mechanism that involves sorting and transcriptional regulation of rbSGLT1. The study findings suggest the involvement of two complementary opposite mechanism of action, in which the balance between two antagonistic effects, namely stimulation and inhibition of the transporter, regulates the activity of rbSGLT1 by PKC.

Resistance training increases muscle mitochondrial biogenesis in patients with chronic kidney disease

BACKGROUND AND OBJECTIVES

Muscle wasting, a common complication in chronic kidney disease (CKD), contributes to poor outcomes. Mitochondrial biogenesis is critical for the maintenance of skeletal muscle function and structural integrity. The present study--a secondary analysis from a published randomized controlled trial--examined the effect of resistance exercise training on skeletal muscle mitochondrial (mt)DNA copy number and determined its association with skeletal muscle phenotype (muscle mass and strength).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Twenty-three patients with moderate-to-severe CKD were randomized to resistance training (n = 13) or an attention-control (n = 10) group for 12 weeks. After a run-in period of a low-protein diet that continued during the intervention, mtDNA copy number in the vastus lateralis muscle was estimated by quantitative real-time PCR at baseline and 12 weeks.

RESULTS

Participants mean age was 64 +/- 10 (SD) years and median (interquartile range, IQR) GFR 27.5 (37.0) ml/min. There were no differences between groups at baseline. Median (IQR) mtDNA copy number was 13,713 (10,618). There was a significant increase in muscle mtDNA with exercise compared with controls (1306 [13306] versus -3747 [15467], P = 0.01). The change in muscle mtDNA copy number was positively correlated with previously reported changes in types I and II muscle fiber cross-sectional area.

CONCLUSIONS

In this pilot study, resistance training was highly effective in enhancing mitochondrial content in patients with moderate-to-severe CKD. This finding suggests that the mitochondrial dysfunction observed with chronic disease could potentially be restored with this exercise modality and should be investigated further.

Thioglycosides as inhibitors of hSGLT1 and hSGLT2: potential therapeutic agents for the control of hyperglycemia in diabetes

The treatment of diabetes has been mainly focused on maintaining normal blood glucose concentrations. Insulin and hypoglycemic agents have been used as standard therapeutic strategies. However, these are characterized by limited efficacy and adverse side effects, making the development of new therapeutic alternatives mandatory. Inhibition of glucose reabsorption in the kidney, mediated by SGLT1 or SGLT2, represents a promising therapeutic approach. Therefore, the aim of the present study was to evaluate the effect of thioglycosides on human SGLT1 and SGLT2. For this purpose, stably transfected Chinese hamster ovary (CHO) cells expressing human SGLT1 and SGLT2 were used. The inhibitory effect of thioglycosides was assessed in transport studies and membrane potential measurements, using alpha-methyl-glucoside uptake and fluorescence resonance energy transfer, respectively. We found that some thioglycosides inhibited hSGLT more strongly than phlorizin. Specifically, thioglycoside I (phenyl-1'-thio-beta-D-glucopyranoside) inhibited hSGLT2 stronger than hSGLT1 and to a larger extent than phlorizin. Thioglycoside VII (2-hydroxymethyl-phenyl-1'-thio-beta-D-galacto-pyranoside) had a pronounced inhibitory effect on hSGLT1 but not on hSGLT2. Kinetic studies confirmed the inhibitory effect of these thioglycosides on hSGLT1 or hSGLT2, demonstrating competitive inhibition as the mechanism of action. Therefore, these thioglycosides represent promising therapeutic agents for the control of hyperglycemia in patients with diabetes.

Role of undecan-2-one on ethanol-induced apoptosis in HepG2 cells

Based on the reduced expression of ethanol-oxidizing enzymes in human hepatocellular carcinoma (HepG2) cells, we analyzed the role of nonoxidative metabolites in ethanol-induced apoptosis in HepG2 cells. For this purpose, an analysis of volatile metabolites of ethanol using ion-mobility spectrometry and gas chromatography-mass spectrometry was performed. HepG2 cells exposed to 1 mmol/L ethanol exhibited significant synthesis of undecan-2-one compared to untreated cells. Undecan-2-one is a fatty acid ethyl ester metabolite synthesized through a nonoxidative pathway. Undecan-2-one had a dose-dependent cytotoxic effect on HepG2 cells as shown by release of lactate dehydrogenase (LDH). The most notable finding of this study was the potentiation of ethanol-induced apoptosis demonstrated by an increased apoptotic rate induced by undecan-2-one in ethanol-treated HepG2 cells. The data presented in this study contribute to the better understanding of the molecular mechanisms of ethanol exposure at low concentration in HepG2 cells, a human hepatocellular carcinoma-derived cell line.

Substrate specificity of sugar transport by rabbit SGLT1: single-molecule atomic force microscopy versus transport studies

In the apical membrane of epithelial cells from the small intestine and the kidney, the high-affinity Na+/d-glucose cotransporter SGLT1 plays a crucial role in selective sugar absorption and reabsorption. How sugars are selected at the molecular level is, however, poorly understood. Here atomic force microscopy (AFM) was employed to investigate the substrate specificity of rbSGLT1 on the single-molecule level, while competitive-uptake assays with isotope-labeled sugars were performed in the study of the stereospecificity of the overall transport. rbSGLT1-transfected Chinese hamster ovary (CHO) cells were used for both approaches. Evidence of binding of d-glucose to the extracellular surface of rbSGLT1 could be obtained using AFM tips carrying 1-thio-d-glucose coupled at the C1 position to a PEG linker via a vinylsulfon group. Competition experiments with monosaccharides in solution revealed the following selectivity ranking of binding: 2-deoxy-d-glucose >or= 6-deoxy-d-glucose > d-glucose > d-galactose >or= alpha-methyl glucoside; 3-deoxy-d-glucose, d-xylose, and l-glucose did not measurably affect binding. These results were different from those of competitive alpha-methyl glucoside transport assays, where the ranking of inhibition was as follows: d-glucose > d-galactose > 6-deoxy-d-glucose; no uptake inhibition by d-xylose, 3-deoxy-d-glucose, 2-deoxy-d-glucose, or l-glucose was observed. Taken together, these results suggest that the substrate specificity of SGLT1 is determined by different recognition sites: one possibly located at the surface of the transporter and others located close to or within the translocation pathway.

Functional genomics analysis of low concentration of ethanol in human hepatocellular carcinoma (HepG2) cells. Role of genes involved in transcriptional and translational processes

We previously found that ethanol at millimolar level (1 mM) activates the expression of transcription factors with subsequent regulation of apoptotic genes in human hepatocellular carcinoma (HCC) HepG2 cells. However, the role of ethanol on the expression of genes implicated in transcriptional and translational processes remains unknown. Therefore, the aim of this study was to characterize the effect of low concentration of ethanol on gene expression profiling in HepG2 cells using cDNA microarrays with especial interest in genes with transcriptional and translational function. The gene expression pattern observed in the ethanol-treated HepG2 cells revealed a relatively similar pattern to that found in the untreated control cells. The pairwise comparison analysis demonstrated four significantly up-regulated (COBRA1, ITGB4, STAU2, and HMGN3) genes and one down-regulated (ANK3) gene. All these genes exert their function on transcriptional and translational processes and until now none of these genes have been associated with ethanol. This functional genomic analysis demonstrates the reported interaction between ethanol and ethanol-regulated genes. Moreover, it confirms the relationship between ethanol-regulated genes and various signaling pathways associated with ethanol-induced apoptosis. The data presented in this study represents an important contribution toward the understanding of the molecular mechanisms of ethanol at low concentration in HepG2 cells, a HCC-derived cell line.

Low concentration of ethanol induce apoptosis in HepG2 cells: role of various signal transduction pathways

As we previously demonstrated in human hepatocellular carcinoma (HepG2) cells, ethanol at low concentration triggers the Fas apoptotic pathway. However, its role in other intracellular signaling pathways remains unknown. Therefore, the aim of the present study was to evaluate the role of low concentration of ethanol on different intracellular signaling pathways. For this purpose, HepG2 cells were treated with 1 mM ethanol for 10 min and the phosphorylation state of protein kinases was determined. In addition, the mRNA levels of transcription factors and genes associated with the Fas apoptotic pathway were determined. Our data demonstrated that ethanol-induced phosphorylation of protein kinases modulates both anti-apoptotic and pro-apoptotic mechanisms in HepG2 cells. Pro-apoptosis resulted mainly from the strong inhibition of the G-protein couple receptor signaling pathway. Moreover, the signal transduction initiated by ethanol-induced protein kinases phosphorylation lead to increased expression of the transcription factors with subsequent expression of genes associated with the Fas apoptotic pathway (Fas receptor, Fas ligand, FADD and caspase 8). These results indicate that low concentration of ethanol exert their effect by predominant activation of pro-apoptotic events that can be divided in two phases. An early phase characterized by a rapid transient effect on protein kinases phosphorylation, after 10 min exposure, with subsequent increased expression of transcription factors for up to 6 hr. This early phase is followed by a second phase associated with increased gene expression that began after 6 hr and persisted for more than 24 hr. This information provided a novel insight into the mechanisms of action of ethanol (1mM) in human hepatocellular carcinoma cells.

Skeletal muscle sodium glucose co-transporters in older adults with type 2 diabetes undergoing resistance training

We examined the expression of the sodium-dependent glucose co-transporter system (hSGLT3) in skeletal muscle of Hispanic older adults with type 2 diabetes. Subjects (65+/-8 yr) were randomized to resistance training (3x/wk, n=13) or standard of care (controls, n=5) for 16 weeks. Skeletal muscle hSGLT3 and GLUT4 mRNA transcript levels were determined by real time RT-PCR. hSGLT3 transcripts increased by a factor of ten following resistance training compared to control subjects (0.10, P=0.03). There were no differences in GLUT4 mRNA expression levels between groups. Protein expression levels of these transporters were confirmed by immunohistochemistry and Western blotting. hSGLT3 after resistance exercise was found not to be co-localized with the nicotinic acetylcholine receptor. The change in hSGLT3 transcript levels in the vastus lateralis muscle was positively correlated with glucose uptake, as measured by the change in muscle glycogen stores (r=0.53, P=0.02); and with exercise intensity, as measured by the change in muscle strength (r=0.73, P=0.001). Group assignment was be the only independent predictor of hSGLT3 transcript levels, explaining 68% of its variability (P=0.01). Our data show that hSGLT3, but not GLTU4, expression was enhanced in skeletal muscle after 16 weeks of resistance training. This finding suggests that hSGLT3, an insulin-independent glucose transporter, is activated with exercise and it may play a significant role in glycemic control with muscle contraction. The hSGLT3 exact mechanism is not well understood and requires further investigation. However its functional significance regarding a reduction of glucose toxicity and improvement of insulin resistance is the subject of ongoing research.

A 96-well automated method to study inhibitors of human sodium-dependent D-glucose transport

The sodium-dependent D-glucose transporter (SGLT) family is involved in glucose uptake via intestinal absorption (SGLT1) or renal reabsorption (SGLT1 and SGLT2). Current methods for the screening of inhibitors of SGLT transporters are complex, expensive and very labor intensive, and have not been applied to human SGLT transporters. The purpose of the present study was to develop an alternative 96-well automated method to study the activity of human SGLT1 and SGLT2. Chinese hamster ovary (CHO) Flp-In cells were stably transfected with pcDNA5-SGLT1 or pcDNA5-SGLT2 plasmid and maintained in hygromycin-selection Ham's F12 culture medium until hygromycin-resistant clones were developed. SGLT1 and SGLT2 gene expression was evaluated by relative real-time reverse transcription-polymerase chain reaction (RT-PCR) quantification, Western blotting, and immunocytochemical analysis. The clones with higher expression of SGLT1 and SGLT2 were used for transport studies using [14C]-methyl-alpha-D-glucopyranoside ([14C]AMG). The advantage of using the 96-well format is the low amount of radioactive compounds and inhibitory substances required, and its ability to establish reproducibility because repetition into the assay. This method represents an initial approach in the development of transport-based high-throughput screening in the search for inhibitors of glucose transport. The proposed method can easily be performed to yield quantitative data regarding key aspects of glucose membrane transport and kinetic studies of potential inhibitors of human SGLT1 and SGLT2.

Ethanol treatment of hepatocellular carcinoma: high potentials of low concentrations

Primary hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide, which is associated with a very poor prognosis. A curative treatment is difficult to achieve and is only possible in a low number of patients. Therefore, many different therapeutic strategies have been developed as alternative treatment. Among these, percutaneous injection of high concentrations of ethanol (>50 mM) has been proven to be effective for the treatment of small HCC (less than 3 cm in diameter). However, the principal problem with using ethanol is its toxic effects on non-tumor cells adjacent to the tumor area. The objective of this review is to juxtapose the therapeutic potential of high and low concentrations of ethanol in the treatment of HCC, based on experimental studies obtained with the human hepatocellular tumor cell line (HepG2). They have shown that high concentrations of ethanol lead to necrosis, while low concentrations induce apoptosis due to activation of Fas-receptors. Triggering of apoptosis through Fas-receptors represents a mechanism of action different from that observed with high concentrations of ethanol, thus, reducing the complications that follow the inflammatory process due to necrosis. Therefore, the use of low concentrations of ethanol could be an effective treatment for HCC.

Percutaneous transthoracic needle biopsy of the lung: review of 612 lesions

PURPOSE

The results and complications of 651 pulmonary fine-needle aspiration biopsies (FNABs) were reviewed. The number of needle passes and needle size were correlated to pneumothorax and chest tube placement rates.

MATERIALS AND METHODS

FNAB of the lung was performed on 651 occasions in 612 patients with 18- to 22-gauge Franseen needles. Diagnostic rates were calculated. The number of needle passes performed and needle size used were evaluated for their association with pneumothorax and subsequent chest tube placement.

RESULTS

Diagnostic accuracy was 94% with sensitivity for malignancy of 95%. Positive and negative predictive values were 99.5% and 90%, respectively. Pneumothorax occurred in 26.9% of patients with 9.2% requiring chest tube placement. Increasing numbers of needle passes and larger needle sizes did not increase the rates of pneumothorax or chest tube placement.

CONCLUSIONS

FNAB of the lung has excellent diagnostic rates and remains the procedure of choice for diagnosing pulmonary lesions. This large study contradicts perceptions that pneumothorax and chest tube placement rates decrease with thinner needles and fewer passes.

[Comparison of liver resection with sequential transarterial chemoembolization in stage pT3 or pT4 hepatocellular carcinoma]

Between January 1990 and January 1996, 39 consecutive patients with histologically improved pT3 or pT4 HCC tumors underwent curative resection (n = 19) or sequential transarterial chemoembolization (n = 20) with a median time interval of 7 weeks up to six times with an emulsion of Lipiodol, Epirubicin and Cisplatin. The 30-day mortality rate for all sessions of TA was 3.8% vs. 21.8% in the resection group (p < 0.05); the cumulative survival rate for the embolization group at 6, 12, 18 and 24 months was 72.3%, 50.1%, 41.2%, 35.4% vs. 42.1%, 31.6%, 31.6% and 14.2% following resection, which cannot be considered statistically significant. Patients with T3 and T4 HCC, treated with sequential embolization or resection, seem to have a comparable survival time.

A retrievable nitinol vena cava filter: experimental and initial clinical results

PURPOSE

The authors describe the properties of a new retrievable nitinol vena cava filter and report experimental and initial clinical results.

MATERIALS AND METHODS

The filters, made of nitinol monofilament wire that forms a spiral cone and retrieval wire, were introduced through an indwelling 5.5-F transfemoral sheath into the infrarenal portion of the inferior vena cava in 10 sheep. In seven animals, four 4 x 30-mm radiopaque clots were injected below the filter to test its thrombus-trapping efficacy. Aspiration thrombectomy was then attempted, and the filter was removed. Follow-up venography was performed 1 week after placement in three other animals. After successful preclinical testing, the filter was implanted and retrieved in two patients.

RESULTS

All 10 filters were successfully and easily placed in sheep. All filters were thrombus-free at follow-up venography. All clots injected in the iliac veins were trapped by the filter and successfully removed by means of aspiration thrombectomy. All 10 filters were retrieved without difficulty. Temporary filter implantation and retrieval were accomplished in two patients for 5 and 7 days. In one patient, infrafilter thrombus was aspirated. Perisheath thrombosis occurred in both patients. One patient subsequently underwent permanent filter placement.

CONCLUSION

Temporary vena cava filtration is feasible. Potential advantages include easy placement, surveillance, and retrieval. One current limitation is pericatheter thrombosis, which may be eliminated by a less thrombogenic sheath.

Complications of laparoscopic cholecystectomy and their interventional radiologic management

Cholelithiasis and cholecystitis are encountered throughout the world and are responsible for the majority of cholecystectomies performed. Treatment has traditionally consisted of open cholecystectomy, but laparoscopic cholecystectomy is currently a popular alternative. Laparoscopic cholecystectomy offers several benefits over the open procedure, but it also has its own set of complications. Complications include those of laparoscopy (abdominal wall bleeding, omental bleeding, abdominal vessel injury, retroperitoneal vessel injury, gastrointestinal perforation, bladder perforation, solid visceral injury, and infection) and those of cholecystectomy (gallbladder fossa bleeding, bile duct injury, bile leakage, and infection). The literature suggests that the total complication rate for the laparoscopic procedure compares favorably with that of the open procedure, but this may apply only to surgeons who have accomplished numerous laparoscopic procedures and not to those who have just completed a training course and are performing their first few procedures. With the growing success of the laparoscopic procedure, it is essential that the radiologist be knowledgeable about the radiographic manifestations and interventional radiologic management of potential complications, since the radiologist can significantly affect patient care.

Prostatic urethroplasty with balloon catheter as a nonsurgical alternative for benign prostatic hyperplasia

Prostatic urethroplasty with a balloon catheter is an easy procedure to perform, but certain guidelines must be followed to avoid complications. This procedure will reduce the overall treatment cost of benign prostatic hyperplasia significantly. Preliminary results range from 70% to 85% symptomatic improvement or resolution of the prostatism symptoms. Its recurrence rate is still not known, but a small one is expected. Nevertheless, because of the noninvasiveness, low cost, and simplicity of the procedure, it potentially could be repeated, if necessary. This procedure is one that when it is done in combination with another specialist, in this case a urologist, the patient will benefit by the use of the expertise of both the urologist's knowledge of the disease of the urinary system and the interventional radiologist's skills with catheters and guide wires.

Two urokinase dose regimens in native arterial and graft occlusions: initial results of a prospective, randomized clinical trial

The effects of two urokinase (UK) dose regimens on lysis time, lytic success, primary clinical success, and frequency of complications of peripheral thrombolysis were compared. Seventy-two intraarterial UK infusions were performed by means of standard catheter-directed infusion techniques in 63 patients with symptomatic peripheral arterial or bypass graft occlusions. Patients were prospectively randomized to high-dose (250,000 U/h for 4 hours and then 125,000 U/h) or low-dose (50,000 U/h) regimens. The mean time to complete lysis was 20.8, 26.0, 16.5, and 18.2 hours for the high-dose artery, low-dose artery, high-dose graft, and low-dose graft groups, respectively (P was not significant). Respective mean infusion durations were 27.1, 35.4, 22.2, and 25.3 hours. Clinical success was achieved in 65%-85% of cases. The frequency of complications was equivalent between groups, except for a higher frequency of minor bleeding complications in the high-dose group. The two urokinase dose regimens studied were equally effective in enabling peripheral thrombolysis.

Reversible hepatic transplant ischemia: case report and review of literature

We report the successful treatment of a hepatic arterial anastomotic stenosis by angioplasty in an orthotopic liver transplant recipient. The patient had already undergone hepatic infarction and compromised allograft function and sepsis. Baseline duplex ultrasound and angiographic studies showed obstruction of the transplant arterial anastomosis. Following angioplasty, allograft function, areas of infarction, and duplex ultrasound studies returned to normal. At 6-month follow-up the patient remains asymptomatic.

New guide wire for high-flow infusion

A new open-ended guide wire with a large internal diameter was compared with two other open-ended guide-wire and catheter infusion systems. Simple experiments were performed to compare flow rates and ability to track. The larger internal diameter of the new wire allowed higher flow rates and accepted an 0.025-inch (0.64-mm) guide wire. The flexibility of the new infusion wire was shown to be equivalent to that of the catheter system. The authors conclude that the new wire has advantages in terms of flow rates and ability to track, compared with presently available infusion systems.

Percutaneous enterostomy with the Cope suture anchor

Eighty-two percutaneous enterostomies were performed at three institutions with the Cope suture anchor for stomach or jejunal wall stabilization during alimentation tube placement. The anchors were successfully placed into the stomach or jejunum in 81 cases. Early in the series, two anchors were misplaced, with no sequelae. There were no other complications at the time of placement. In all successful cases, excellent immobilization of the viscus was achieved. Tract dilation and tube placement were easily performed, and there were no guidewire or tube dislodgments.

Perineal abscess after prostatic urethroplasty with balloon catheter: report of a case

A 72-year-old patient underwent uneventful prostatic urethroplasty by means of a balloon catheter. The immediate follow-up retrograde urethrogram failed to demonstrate any areas of extravasation and showed a significant increase in prostatic urethral caliber. Three weeks after the patient was discharged, computed tomography demonstrated a large perineal abscess that was attributed to either the prostatic urethroplasty or subsequent Foley catheter manipulations. The abscess was drained percutaneously, and the patient recovered uneventfully. It was concluded that the abscess was a possible isolated complication and that the procedure is warranted in an adequate clinical setting.

Percutaneous intravascular biopsy using a Simpson atherectomy catheter: technical note

The design of the Simpson atherectomy catheter makes this device a potentially safe and technically easy tool to obtain adequate pathologic intravascular or intraluminal specimens. The risk of perforation should be low, but this use has to be further studied. We describe the first intravascular biopsy performed with the Simpson catheter.

Double-lumen needle for percutaneous ureteral pressure-flow studies

Ureteral perfusion studies in patients without preexisting renal access currently must be intermittently interrupted for intrarenal pressure measurement. A double-lumen needle has been successfully placed in four patients (two with native and two with transplanted kidneys). This permits simultaneous perfusion and intrarenal pressure monitoring yet maintains the safety and ease of use of a single skinny needle.

Thrombosed polytetrafluoroethylene hemodialysis fistulas: salvage with combined thrombectomy and angioplasty

Combined thrombectomy and angioplasty was performed for 19 thrombosed polytetrafluoroethylene grafts. Patency for more than 1 week was achieved in 16 of the 19 grafts (84%). The average duration of graft function after angioplasty in all 19 grafts was 7.1 months (range, 0-32.3 months). Eleven of the 19 grafts (58%) were functioning 5 months after the procedure; seven are still functioning. Combined thrombectomy and angioplasty offers a viable alternative to thrombolytic therapy or complete surgical revision.

Percutaneous atherectomy as an alternative treatment for postangioplasty obstructive intimal flaps

Intimal flaps are commonly seen angiographically after percutaneous balloon angioplasty. Nonobstructive flaps are normally of little clinical significance, but flaps that obstruct blood flow may lead to partial or complete thrombosis. The Simpson atherectomy catheter was used to treat obstructive intimal flaps after angioplasty in four patients. Lumen patency was reestablished in all four cases. The clinical results were excellent, with rest pain and claudication resolved in all four patients and distal pulses reestablished in one. These findings suggest that the Simpson atherectomy catheter can be used to remove large obstructive flaps complicating angioplasty.

A new technique for introduction of large instruments into the vascular system

A new introducer system for large devices is described, which is easily manufactured from commonly available materials in a hospital environment.

Alternative treatment of prostatic urethral obstruction secondary to benign prostatic hypertrophy. Non-surgical balloon catheter prostatic dilatation

Benign prostatic hypertrophy (BPH) produces symptoms that currently can only be treated surgically either by open or endoscopic prostatectomy. We have undertaken animal (1) and human studies to determine if invasive radiologic techniques utilizing balloon catheters could be applied to the treatment of this common ailment. We report a series of twelve patients treated by retrograde transurethral balloon catheter prostatic dilatation. The procedure is performed using topical anesthesia with a specially designed balloon catheter (Medi-Tech, Inc.). The procedure is done on an outpatient basis and is completed within approximately 15 minutes. Relatively long-term results have resulted in persistent relief of symptoms. No complications have been encountered. We anticipate that balloon dilatation of the prostatic urethra will have a major impact on the treatment of BPH based on the promising preliminary results. Transurethral resection of the prostate (TURP) is associated with moderate morbidity and significant cost which can be reduced by the proposed procedure.

Benign prostatic hypertrophy: retrograde transurethral dilation of the prostatic urethra in humans. Work in progress

Retrograde transurethral balloon dilation of the prostatic urethra was performed in five human volunteers with benign prostatic hypertrophy. Each patient underwent cystoscopy, uroflow studies, voiding cystourethrography, retrograde urethrography, and magnetic resonance imaging before dilation and at defined intervals afterward. The longest follow-up to date is 8 months. Patients were given topical anesthetics and mild sedatives, and dilation was performed with a 25-mm urethroplasty balloon catheter inflated at 3-6 atm for 10 minutes. All catheter manipulations were done with a guide wire and under fluoroscopic control. Significant resolution of symptoms of prostatism was seen in four patients. The unsatisfactory results in the last patient were believed to be caused by ineffectual dilation of predominantly middle lobe hypertrophy--a condition that is now regarded as a contraindication to dilation. This technique has promise to replace transurethral resection of the prostate as the treatment of choice for this common male ailment.

Prostatic urethra: experimental dilation in dogs

An animal study was undertaken to develop a balloon dilation technique that could be used in humans to treat the common ailment of benign prostatic hypertrophy. Dogs were used as a model because of the similarities in the prostate between the two species and the ready availability of the canines. A retrograde transurethral approach was used for dilation. Balloon catheters, 8-20 mm in diameter, were used. Significant, long-lasting dilatation of the prostatic urethra was not accomplished until 20-mm balloons (or two 10-mm ones) inflated for 10 minutes were used. The animals were followed for up to 14 months. No deleterious histologic effects of dilation were identified within the urethra or prostate that could lead to stenosis of the prostatic urethra in later stages.

Prostaglandins and angioplasty. An experimental study in canine arteries

To prevent platelet aggregation following percutaneous transluminal angioplasty (PTA), cyclooxygenase inhibitors such as acetylsalicylic acid (ASA) and indomethacin are recommended. However, ASA blocks both the proaggregating effects of thromboxane (TXA2) and the antiaggregating and vasodilating effects of prostacyclin (PGI2). The authors measured the contractile response of dilated canine carotid arteries in situ and in vitro using an isometric force transducer. Following PTA, contraction of the arterial wall was significantly reduced (p less than 0.01). By blocking cyclooxygenase with indomethacin (3 micrograms/ml), contraction was greatly improved (p less than 0.001). These results suggest that PTA may result in marked release of prostacyclin by the damaged arterial wall, which could account for the decreased responsiveness of the artery to exogenous norepinephrine.

Patency of the ductus arteriosus after balloon dilatation: an experimental study

Balloon dilatation of the ductus arteriosus was carried out in vivo in newborn pigs and on postmortem specimens from humans and piglets. The ductus was functionally closed in all newborn animals but patency resulted in all animals after balloon dilatation. Left-to-right shunts of 50% to 70% were found with anatomic lumen sizes of 3 to 5 mm. Patency was demonstrated up to 6 weeks after dilatation. Histologic examination showed splitting of the internal elastic layer and media, areas of hemorrhage confined to the media, and preservation of the adventitia. Mediastinal hemorrhage did not occur. This new technique is useful as an animal model of patent ductus arteriosus and could theoretically be used for palliative treatment of ductus-dependent congenital heart disease.

A new percutaneous vena cava filter

A new, percutaneous vena cava filter was developed and tested in 11 dogs. Nitinol wire (0.045 cm diam) spirals were straightened and passed through an 8 French Teflon catheter into the inferior vena cava. The filter resumed its original spiral shape on warming to body temperature and was left in place up to 6 weeks. Long-term patency and capture of injected radiopaque clots were demonstrated. This new filter design may be a simple alternative to currently used implants.

Detachable stainless-steel spider. A new device for vessel occlusion

A new device for transcatheter vessel occlusion consists of a stainless-steel spider which can be screwed onto a threaded guide wire. Since the spider can be retrieved after it is extruded from the catheter, accurate placement is possible. The device was tested in the aorta and pulmonary artery of dogs. The spider blocked the movement of steel coils and wool streamers and occluded the vessel. This device is particularly useful for occlusion of large arteriovenous fistulas in the lungs.

Nonsurgical placement of arterial endoprostheses: a new technique using nitinol wire

A new type of endovascular prosthesis has been developed using a unique metal alloy (nitinol) with a heat-sensitive memory. Nitinol wire coil grafts were straightened in ice water and passed into the canine aorta via catheter, where they reformed into their original shapes. Follow-up aortograms demonstrated long-term patency with minimal thrombus formation. Nitinol endovascular coil grafts may eventually be used in the nonsurgical treatment of several forms of vascular disease.